Main functions of MPPT controller: check the dc voltage and output current of main circuit, calculate the output power of solar array, and track the maximum power point. Disturbance resistance R and MOSFET string together, under the condition of stable output voltage, by changing the duty ratio of MOSFET, resistance to change by the average current, so the current disturbance. At the same time, the output current of photovoltaic cell voltage will also be changed, by measuring the perturbation pv cells before and after the change of the output power and voltage, to determine the disturbance direction of the next cycle, when the disturbance in the right direction solar energy panels output power increases, the cycle is to continue in the same direction perturbation, on the other hand, the disturbance in the opposite direction, so, the iterative perturbation and observation to solar pv output of maximum power point.